Slow at 2/3 battery

[Fairtax4me]

Originally Posted by Tom47

This is a story no one on BGW will believe, so I never told it here. This will be just between you and me.

I bought my DS in 2016. The batteries had the plates exposed on about 1/2 the cells. It had just enough power to drive it up on my trailer.

When I got it home it took about a gallon of distilled water to bring the electrolyte level up. Hooked up the charger and let it go overnight. The next morning it ran fairly well at 12 to 14 mph for a couple miles.

Well, that was 4-1/2 years ago. Everything was replaced in 2017.....except for the batteries. I keep waiting for them to stop holding charge so I can get new ones, but they keep on going. They are date code C13.

I'll probably go with ECO Battery lithium, 72 AH, when and if they die. They may last longer than me!

Slightly exposed, or totally dry?
Seen plenty of batteries where the tops of the plates are above the water line, but they're still wet. It doesn't look great, but it's not as detrimental as it sounds.
The real damage occurs if the plates go totally dry. Water so low you can't even see it between the plates.
Lead acid batteries have two different plate types. The positive plate is made of lead Oxide, and the negative plate is made of a porous lead which is mostly pure lead. The lead oxide has a different number of electrons, which is what creates the ability for electricity to move between the plates when they are exposed to an electrolyte.
When the plates go totally dry, the exposed area of the negative plate oxidizes. It essentially becomes the same charge as the positive plate, which means there is little or no ability for electrons to flow from plate to plate. So if 20% of the plate went dry and became oxidized, you lose about 20-30% of the capacity of that cell.

But whether anyone notices the loss of capacity depends how long they want to use the cart for. Some people only go 1/4 mile a day, probably wouldn't tell the difference.

If the tops of the plates are visible, but still wet, probably fine, or minimal damage.
If they're totally dry and no water visible at all, that's permanent damage, and no way to fix it.

[Tom47]

Thanks, Fairtax.

The top of 1/2 the plates were damp and I could still see the electrolyte around the plates. The other half were just barely submerged.

It took about a gallon of water and I probably overfilled them almost to the level "eye". I try to keep them half way between the eye and the top of the plates since then.

By the way, although the batteries enable me to go far and return with very good SOC readings, I noticed I can no longer reach 25 mph as I did in the past with a 24 nominal top speed. Now I have a nominal 22 top speed with occasional 23's. I have decided to replace them with LA batteries when the time comes. I've heard too many problems with drop in lithium to go that route for now.